This invention relates to lasers and, more particularly, to a gas ion laser having an electrically conductive electrode, such as an anode, adhered directly to ceramic of the laser tube. A principle component of a gas ion laser is a laser tube. The laser tube defines a containment volume for a gaseous lasable medium and generally includes window structures at its opposite ends to permit escape from the tube of the optical radiation which results from lasing action. The tube is positioned between a pair of spaced-apart optical reflectors which reflect radiation emitted by the medium back-and-forth through the tube, to cause the stimulated emission of optical radiation from the medium. The space between the reflectors generally is called the "optical cavity" of the laser, and the imaginary line which passes between the reflectors centrally through the tube is called the laser "optical axis".
One of the reflectors usually is partially transmissive to permit optical radiation to escape from the laser optical cavity and thereby form an output beam of coherent radiation. It is necessary that the optical reflectors be maintained in a selected, rigid and spaced-apart relationship to define the optical cavity and assure that lasing action will take place and be maintained. This generally is obtained by mounting the optical reflectors on mounting structures which, in turn, are precisely positioned relative to one another by structure extending therebetween. The mounting structures and the structure extending therebetween typically is referred to as a "resonator" of a laser.
Many medical uses have been found for the coherent radiation output of gas ion lasers. For example, ion laser output is used for macular photocoagulation. Thus, ion lasers are often a dominant part of instruments which now are finding use in hospitals, clinics, the offices of doctors, etc. It will be recognized that in order to assure reliability in these many different environments, it is important that the laser itself be rugged. For this reason, among others such as low dimensional changes due to thermal variations, many manufacturers are making most of the components of an ion laser tube out of a ceramic, such as beryllium oxide or aluminum oxide (alumina). While a ceramic is relatively rugged, it is difficult, if not impossible, to provide feedthrough through the same for the necessary electrical connections internally to an anode or cathode. It therefore often is a practice to include parts of metal or other non-ceramic material adjacent the anode and/or cathode. Moreover, the anode (and cathode) must be electrically conductive and therefore is itself often a metal.
The seal formed between metal and ceramic parts of a laser constitutes one of the structurally weakest areas of a laser tube. Thus, the electrode aspects of a laser tube are generally one of the least rugged and least reliable parts of the same.